Condenser and circuit therefor



Nov. 16, 1943. F. 0. WEBSTER CONDENSER AND CIRCUIT THEREFOR Filed Jan. 22, 1942 3 Sheets-Sheet l FIGJ.

llll. IIIIIIHUH IN VEN TOR.

Y 5E ym mm W A p M 7 m lm Conduciz'rc yroundcl porza'on of 226 vacuum fafie.

Nov. 16, 1943. F. D. WEBSTER 77 2,334,660

CONDENSER AND CIRCUIT THEREFOR Filed Jan. 22, 1942 3 Sheets-Sheet 2 w i llll i nn I IN VENTOR.

A T TORNE Y.

Nov. l6, 1943.

F. D. WEBSTER 2,334,660

CONDENSER AND CIRCUIT THEREFOR Filed Jan. 22, 1942 5 Sheets-Sheet 3 INVENTOR- ATTORNEY.

Patented Nov. 16, 1943 I eoNmiNsEnsifi fiifj hmrnmsroe;

Fullerton n. Web ter, Mount in La es N Y This invention relates tot-electrical condensers and has for its object to provide a condenser arraingement for connecting to ground the cathodes It is well: known that parasitic voltagesand currents tend: to develop in the filament circuits of vacuum tubes at high freii'uencies; and there create undesirable efie'cts, such as parasitic oscillations. It is also well known thatit thetube cathode is placed at radio frequency ground potential; the tendency toward parasitic oscillationis greatly-reduced,owing-tothe fact that the leads to the cathode are effectively eliminated from the radio frequency circuits.

According'to this inventioma small, compact by-pa-s's condense'i is mounted directly adjacent the'tubeterminals and connecteddirectly" between the terminals and ground; and mean'smay be provided for connectingthe-pqwcn-leads-to the condenser; A feature is an arrangement of a condensenunit which may-be used with a polyphase filament to connect-each-filament-terminal with ground A- related feature is a condenser assembly which may be placed asa unit between the tubeterminalsand' the power leads which supplythe heatlngcurrent.

Referring to the drawings,

Fig. 1 is an elevation view of a. condenser ate; tached to the cathode or heater terminals; a vacuum tubeeand to power leads, accordina to-this invention;

Fig. 2 is. adplanview of the condenser: taken, at limit-40f Fig. 1; Ei :is.a;.view, frqmrthevbpttqm Qt he QQ? denser taken amine: M-E s- Ls.

E 2. at s ap an visw 91; ne. 9;: the pl l sfi;

s- 5 s a irihss is lhm hqwhs she-hiss: Q- hh hs the s ns shls h w th: s s-2 w fi e hisn f a FW- mm? In Fig.1 there iscshqwn a vacuum tube hayinga, mem bes n f i n', tahd' but 1 a wall? hi h may be q ass, A n u 'f i ll 1, at e r fil meiht m nals bromide li ivaiqlx throiih the b ss and le tris x ih hlet 'thsrsi ml zws hk wh mahhe T e are ShOWh six of these filament terminals, which is the number required for afs'ix phase filament; although it will" beunderstood that the number of terminals win he dependent upon thetype of: filament or cathode employed:

There is shown in Fig. a wiring diagram of a slir phase fila rnent which might be iised i'n the.

tube. Thiscomprises the six filaments- '4 are ranged in a stariconnectionvwhlch might, be

in alerssatuhe su h ssewatsmoded he electrical center of the star connection ground: 51: a 5,7 and. the; insmundsdterminals 3 of sash fila e t are, e on ected to h t n is ai s 31313 8 Thefilamentsa e; e er ze y curre t-A sup ied from. the secondar o s. Qi: tME- QHRQQEQ mwehrahsm msh each ra sormer: econda y avin ts; te i al: mmit e to opposit pairs filament t rminals In order to ground the fi aments w h respe t Q hi hefnequericy currents. the e shou d: b 9 nested across. e h pair of filam n s rec v n power om a, secondar coi a pair. o 91 snse s 1 and a an ed miserie and-conne t dto ground between them at 8; These condensers are preferably of equal capacity; and, of: a relatively low high frequencyimpedance;

'Ehe group o -cbyspass; ndensers; LI s efiiqisntly'and; compac providedby he. on en e nit-Va ane msnt; illus r te i nfi 1 q 4, wh ch is co stru tedandsahmhs d h s r h o the vacuu n tube-terminals ,to provide the; desired bypass csnacities ith e y sh r l c cal o ec tions from the tuhe. The condenser is arranged ass mh nls uhitmmp isi s plura i or. m tsll c. la es 8 sand i hed e we n insulating nlat si rshss s Bs w eh h v hdi h n of; theseinsulatlng sheets there is placed a metellic sheet li which is preferablyv thicker than. thethihh n eta i shee s e e s P a d a ainst: l ech c te ns la g sh et relatively heg vy metallicsheet 12. The conducting h ets, 9 and: 2: e elect ca y onne t d; and boundtogether-at theedgesot the stack by. meaflbmexnbsm 13 whi h ar Pre l s de e or therw se suitabl! ias h d these Pla es I! and 9.: Ri s em inin on u t g plat s 1 which alternate with theplgtes- Sin the stack, are of smallerdiameterthan plates! and are'not contacted bymembers I73 or plates Sand; I2 and are insulated therefrom. The-stack is securely held together by means: ofa. number of bolts; such as l4; equally spaced which: pass through the stack from top to bottom andhave the nuts lPsultably tightened up. The plates; l2 and 9 are attached to a fsi itahIesupporting wall such as 15 which may he done suitable nieans such as a rigid bar It; fastened to theupper plate by a nut and bolt drranssmenuiana; to the wall I5-by a.

' su t bl ngle p e 's fi a tifbo ts n 2 The s em ly O conn ted plates! and I2, is di ectly sisiih imt ihe m n s bases In r thsmbsb'y asmis r-i whishh rhe b lte time b t m pastel-2w nu sndhsai a shiieiih h fl at i opposite end by a suitable clip 22 to a bolt or protuberance 23 protruding from base I.

In this arrangement each ungrounded plate provides capacity through the adjacent insulating plates ill to the grounded plates 9 (or l2) on either side. It is accordingly required that plates I to be insulated from the grounded plates and from all grounded bolts, and also that provision be made for providing connecting terminals to the plates II. For this purpose, the plates H are constructed as shown in Fig. 4. They are provided with a set of six holes 24, 25, 26, 21, 28 and 29 equally spaced around the circumference.

They are also provided with a number of holes 30 within the outer circle of holes, the holes 30 being for the passage of the binding bolts l4. Holes 24, to 28, and also holes 30 are clearance holes so that bolts or studs may pass through without touching the plate. They are accordingly made large. Hole 29 is provided for attachment with a terminal stud and accordingly is made small.

The condenser unit illustratedcontains a total of seven grounded plates'9 and I2, this total being one more than the six of the plates I corresponding as this corresponds with the number of the filament terminals in the six phase connection; and all these plates H are made identical so that the holes of all the plates will overlie each other, except that each separate plate has a difierent one of the outer six holes 24 to 29 made small. Thus the second plate 'will have hole 24 made smalland holes 25 to 29 large, and the third plate will havehole 25 small and holes 26 to 29 and 24 large. Holes 3|! are of the same size in each plate.

The groundedplates 9 and I2 will be made identical to plates except that in plates 9 and l2 all of the outer circle of holes corresponding to holes 24 to 29 in Fig. 4 will be made large for clearance, and there will be no small hole such as 29. Plates 9 and I2 are of greater diameter than plates II, also holes 30 0f plates 9 and I2 are made small for clearance of bolts l4.

The ungrounded condenser terminals are provided by studs 3|, the shank portion 32 at the head and being of relatively large diameter and the threaded portion 33 at the other end being of smaller diameter than the shank. Each stud is provided with a nut 34 which is preferably of the same circular cross section and diameter as shank 32. The nuts 34, have connected to them as by sweating, suitable electrical leads 35 which are the filament power leads. The terminal studs SI and their nuts 34 preferably all have the same overall length, but the relative lengths of the nut to the shank varies from one stud to another, as shown in Fig. 1, to allow connection to different ones of the ungrounded plates ll. ance holes 24 to 30overlie eachother. The first of the studs will then be placed through the alined holes, all of which will be clear of the stud, except the one having the small hole 29 (Fig. 4) which may be the upper plate H as shown in Fig.1. The nut 34 will then be tightened down against this plate to grip it between the nut and the shank, thus providing a terminal connected to this plate II but not connected to any other plate or grounded member. The next terminal stud will similarly pass through another of the holes, for example holes 28 of which the one in second plate from the top may be the small hole to which the stud may be attached. In this manner a diiIerent stud is fastened to a different The stack is arranged so that all the clearone of plates II, and is insulated from all the others.

The bolts M which bind the unit together are suitably insulated from all the plates II by reason of the clearance provided by hole 30, through which the bolts pass. The remaining plates 9, I0 and I2 must also have their clearance holes alined with holes 24 to 29 so that none of the studs touch these grounded plates; and the insulating sheets will also have holes alined. These grounded plates and insulating sheets must likewise have holes corresponding to and alined with holes 30, but it is immaterial whether they be made large enough to clear the bolts I! which pass through them and bind the stack.

Suitable leads 36 are connected with the studs 3| and these are preferably made flexible and connected with a suitable clamping unit 31 for connecting with the corresponding filament terminals 3. Clamps 31 may be of any suitable design; for example, they may comprise a slotted member 38 which passes over the filament terminal and'is clamped tightly by screws 39. As a different one of the leads 36 is connected to a different one of the tube terminals the condenser connections to these tube terminals and ground will be as shown in Fig. 5.

By reason of this construction and connection arrangement there is provided a compact, multiple condenser unit which connects each filament terminal by a very short lead through a condenser to ground, thus minimizing the length of the radio frequency path to ground, and reducing the tendency toward parasitic currents. There is furthermore provided a ready means for connecting the power supply leads without any long connections between the tube terminals and the condensers and which do not need to be disconnected to change tubes. This is of much importance in the use of high power tubes such as the water cooled type where the power leads are heavy and cumbersome.

It may sometimes be desirable not to ground the filaments, as for example when it is desired to place a biasing voltage on the filaments. In such case, there should not be used a direct connecting link 2| betweenthe base ring I and the grounded part of the condenser. Instead, the connector 2| may be broken and a by-pas condenser connected between the broken ends thereof. This will have the effect of placing the condenser in the lead 5 of Fig. 5, between ground and the filament midpoint, inasmuch as the filament midpoints are connected to the ring The high frequency currents will still, in efiect, be at ground potential inasmuch as the condenser to be placed in lead 2| should be of sufiiciently low reactance to form a low impedance path to ground. If desired, the condenser which would be connected in lead 2|, in this manner, may be built into the unitary condenser itself simply by adding another plate I and accompanying plate I0. In such case, there would be placed a seventh terminal around the circumference of the unit and seven holes instead of six holes around the circumferences of plates H], II and I2. The conductor 2| from terminal 23 would then be connected to the seventh terminal of the condenser to provide the condenser connection from ring I to the grounded frame I5.

The/use of the unit is very convenient as when it is desired to change a tube, all that i required isto loosenclamps 31 and clip 22, removebolt l9, and'lift the condenser assembly and swing it.

to one side. The tube can then be replaced and the condenser swung back and assembled.

Although the particular arrangement described is adapted for use with six-phase filaments, it will readily be understood that the arrangement could just as easily be made to be adapted to a tube having a different number of filament terminals.

What is claimed is:

1. A multiple condenser unit for grounding the terminals of a polyphase filament for a vacuum tube, said unit comprising a plurality of conducting laminations separated by insulating laminations, alternate ones of the conducting laminations being connected together and totaling one more than the number of the other alternate conducting laminations, a separate filament connector terminal stud connected individually with each of said other alternate ones of the conducting laminations, each of said studs comprising a shank portion and a binding member for binding the stud to its respective conducting lamination, there being corresponding clearance holes through all of the conducting laminations to which the stud is not connected, through which said stud protrudes from both sides of the conv studs comprising a shank portion and a binding member between which the respective conducting lamination is bound to the stud, all of the conducting laminations to which the stud is not connected having a corresponding clearance hole through which the stud protrudes from both sides of the condenser stack, said studs being connected from one side of said stack to said filamentary terminals, and the connection from the first alternate conducting laminations being connected to a grounded portion of said tube.

3. In combination, a vacuum tube having a polyphase filament having a terminal individual to each phase of said filament, each said terminal protruding from said tube and a multiple condenser comprising a plurality of conducting laminations separated by insulating laminations, alternate ones of the conducting laminations being connected together and totaling one more than the number of other alternate conducting laminations, a separate terminal connected individually with each of the other alternate ones of the conducting laminations, all of the conducting laminations to which a terminal is not connected having clearance holes aligned so that the stud protrudes from both sides of the stack without touching any of the conducting laminations other than that to which it is connected, a connection from said filament terminals to the studs protruding from one side of the stack, and fila- I ment voltage supply leads connected to the studs protruding from the other side of the stack, the connections from said filament terminals to said studs being sufficiently short so as to position said multiple condenser sufiiciently close to said filament terminals to serve as a shield for the latter.

' FULLERTON D. WEBSTER. 

